The invention concerns security documents, in particular value-bearing papers, comprising at least one security element on a surface of the substrate forming the security document and/or at least one window-like opening in the substrate, forming at least part of a security element.
Value-bearing papers, in particular banknotes, check forms, share certificates and so forth are increasingly provided with security elements which make forgery more difficult and which are intended to permit a check on authenticity even for a lay person, without involving major difficulties. A corresponding consideration also applies in regard to other security documents, for example identity cards and passes, visas and so forth. In that respect, the security elements which are being used to an ever increasing extent are optically variable or optically effective identifications, for example structures having an optical-diffraction effect, for example holograms, partially reflective surface regions and so forth. It is further known to increase the level of security of value-bearing papers by special printing processes or also to use special substrates, whether paper or plastic material, for the production of corresponding value-bearing papers, in particular banknotes. In this connection the use of given printing processes or the use of special substrates already provides that the surface of the corresponding security document, in particular a banknote, acquires a quite specific roughness or structure which is perceptible to the human sense of touch. It will be noted however that the tactility which is achieved by virtue of the special printing process or the substrate material used is not of prolonged duration, particularly in the case of value-bearing papers which are frequently in use such as banknotes. More specifically the surface nature which arises by virtue of the special printing process or the material used is generally altered very quickly when using the banknotes or the like because perspiration, dirt or other foreign materials accumulate on the surface or the surface changes comparatively quickly as a consequence of mechanical loading and the effect of moisture.
It is already known from DE 43 34 847 to provide value-bearing documents with a window which is subsequently introduced into the substrate but which then in turn is closed with a film which is at least region-wise transparent. Such a window can admittedly be felt by means of the sense of touch. It is however not suitable for actually forming a reliable tactile security element unless there are additional specific safeguard measures in the region of the film closing the window or the usual substrate of the value-bearing paper so that it is not possible to at least make it difficult to copy such items, in a simple fashion.
Finally, it is also already known for banknotes to be provided with special structure features which can be sensed by blind persons or visually impaired persons in order to enable them to establish the value of the corresponding banknote. Those visual impairment guidance features however are also not suitable as general security elements because they can be correctly sensed and recognised by tactile means only by especially trained users. In addition circulation-related influences can cause a marked reduction in tactile perceptibility.
Further documents with security elements are known from the following publications:
DE 101 62 050 which was published after the relevant date describes a data carrier printed with a tactile half-tone image and a process for the production thereof.
DE 100 44 464 describes a data carrier having a security element which can be at least visually checked and which has an embossing on a partial region thereof.
DE 199 63 849 also claims a data carrier having a printing security element comprising a plurality of structure elements, wherein a part of the structure elements is relief-like and can be felt by touch.
DE 100 15 097 describes a data carrier which is printed upon using piercing intaglio printing.
DE 1 632 482 describes a forgery-proof identity card comprising a plastic material sheet with a writable coating. In an embodiment of the identity card the writable coating has grid-like openings which are of such a small diameter that the coating is writable.
DE 946 585 discloses a stick-on value stamp.
DE 2417549 describes a process for the production of patterns which make forgery more difficult, in value-bearing papers, wherein it is provided that a pattern is introduced into the value-bearing papers by abrading.
DE 43 42 964 describes a technical process for the production of banknotes which afford a safeguard against forgery by copying. That process provides producing an opening, for example a window, in the banknote. That opening is filled by a woven, braided, knotted or glued inlay of lattice material which is introduced into the center between the banknote layers, similarly to the known silver threads.
DE 195 36 461 discloses value-bearing printed transaction units, for example tickets or the like, with cut-out opening patterns.